Switching device



Feb. 7, 1961 E. 1.. SCHIAVONE 2,971,120

SWITCHING DEVICE Filed Nov. 4, 1959 61 i g ,gw'az g 4/ ATTORNEYS INVENTOR United States Patent SWITCHING DEVICE Edward L. Schiavone, 10502 lnsley St., Silver Spring, Md.

Filed Nov. 4, 1959, Ser. No. 850,829

Claims. (Cl. 315-43) This invention relates to a switching device and more particularly to a switching device adapted for use with.

photoelectric devices. This is a continuation-in-part of my application Serial No. 753,833, filed August 7, 1958.

Priorly, numerous types of switching devices have been employed in electronic systems such as those systems which produce information containing images from electrical signals. Examples of these devices and systems are disclosed in Piper Patent 2,698,915, Livingston Patent 2,774,813 and Peek, Jr. Patent 2,818,531. The Piper patent is directed to the phosphor screen per se and includes a layer of electroluminescent material between co-operating groups of parallel conductors positioned on opposite sides of the phosphor layer and at an angle of 90 with respect to each other. The latter two patents disclose various methods of selectively energizing the conductors in the panel of the type disclosed in the Piper patent.

In order to produce a satisfactory visible image comparable to that obtainable on a cathode ray tube, it is necessary that the panel have a large number of closely spaced, small conductors. in order to produce suitable contrast between the light and the dark areas, it is necessary that these conductors be selectively energized and the degree of energization be proportional to the desired intensity of illumination. Since the primary object of these image production systems is the elimination of the cathode ray tube, the resulting system must represent a simplification of circuitry, a reduction of size and number of components and, most important, a reduction in cost.

Accordingly, it is an object of this invention to provide an improved switching device which may be employed with the panel type screen.

It is another object of this invention to provide a unitary switching device which is compact and simple in construction.

It is another object of this invention to produce an improved device for selective energization of a large number of photoelectric devices.

It is another object of this invention to provide an improved optical device for selectively actuating a plurality of photoelectric devices.

It is another object of this invention to produce a unitary optical device suitable for selectively energizing discrete areas of fluorescent material.

Briefly, this invention comprises a switching device enclosed in a single elongated envelope and which may be electrically isolated from the circuitry of the phosphor screen. The device includes an elongated line of fluorescent material, preferably running substantially the entire length of the envelope. An elongated cathode or other suitable source of electrons is positioned within the envelope and runs substantially the length of the envelope with its axis substantially parallel to that of the fluorescent material. Two pairs of elongated deflector plates are positioned between the fluorescent material and the source of electrons. The pair of deflector plates nearer the cathode or source of electrons is positioned with its axis defining a small angle with respect to the axes of the cathode and fluorescent material and may have a constant direct current potential applied therebetween. The narrow, elongated beam of electrons leaving the source or cathode is in the form of a sheet moving in an edgewise direction which enters the region between the first pair of deflector plates and this elongated beam undergoes a slight rotation. The second pair of deflector plates, which is nearer the fluorescent material than the first set of plates, is positioned with its axis substantially parallel to the axes of the fluorescent material and the electron source. When a deflection voltage: of varying magnitude is applied to this second set of deflector plates, the canted or twisted sheet of electrons will be moved perpendicularly with respect to this second set of plates and thus define a relatively small intersection or area of c0incidence with the elongated line of fluorescent material.

If a large number of photoelectric devices are posi tioned in a line adjacent the line of fluorescent material and externally of the envelope, these photoelectric devices will be selectively energized when the discrete area of fluorescent material is energized. Advantageously, the circuitry of the photoelectric devices may be completely electrically isolated from the switching device. Accordingly, if each of the conductors of the phosphor screen is connected to a photoelectric device, such as a phototransistor, positioned adjacent the end of the conductor and the envelope containing the switching device is positioned adjacent this line of phototransistors, the associated conductors in the phosphor screen can be selectively energized through the operation of the switching device. A similar switching device may be employed on the co-operating layer of conductors in the phosphor screen. Advantageously, more than one layer of conductors may be employed and the conductors in parallel groups of layers may terminate in phototransistors or other photoelectric devices which are, advantageously, interspersed to define a single line of photoelectric device adjacent the switching device of this invention. With such an arrangement a color image may be produced.

Accordingly, it is a feature of this invention to employ in a switching device a line of fluorescent material, an elongated source of electrons having its axis parallel to the axis of the fluorescent material and means intermediate the source and the material to selectively energize a discrete area of the material.

It is another feature of this invention to employ as a switching device an elongated source of electrons positioned within an envelope, an elongated line of fluorescent material positioned with its axis substantially parallel to the axis of the electron source and pairs of deflector plates intermediate the electron source and the fluorescent material, the first of the pairs of electrodes being positioned with its axis at an angle with respect to the axes of the electron source and the line of fluorescent material.

It is another feature of this invention to employ in a single envelope an elongated source of electrons, an elongated line of fluorescent material positioned with its axis substantially parallel to the aXis of the electron source, a first pair of deflector plates positioned with its axis disposed at an angle with respect to the electron source and the fluorescent material and a second set of deflector plates with its axis substantially parallel to the electron source and the line of fluorescent material, each of the pairs of deflector plates being disposed on opposite sides of the path between the electron source and the line of fluorescent material.

These and various other objects and features of this invention will be more clearly understood from a reading 3 of the detailed description in conjunction with the drawing, in which:

Figure 1 is a plan view, partly in section, of the switching device in accordance with this invention;

Figure 2 is a diagrammatic representation of a portion of the device of Figure 1 taken along the lines 22 of Figure 1; and

Figure 3 is an isometric representation, partly in schematic form, of one illustrative combination employing the switching device.

Referring now to Figure 1, there is depicted, partly in section, a switching device 8 in accordance with this invention in which 10 designates an elongated tube of transparent material such as quartz or glass. The numeral 12 designates an arcuate, elongated thermionic cathode which extends substantially the entire length of the envelope 10 with its axis parallel to the axis of the envelope and having a heater element 11 which includes an emissive surface 13. A clear plastic insert 14 is positioned in the envelope 10 and has a slot 16 extending longitudinally thereof, which slot is filled with fluorescent material 18. A translucent anode 17 touches the fluorescent material to provide an electrical contact. The axis of the slot 16 is parallel to the axis of cathode 12. Heater 11 is connected to a suitable source, not shown. while source 21 may be connected between cathode 12 and anode 17. Source 21 may apply a direct potential between these electrodes in the conventional manner or it may apply a modulated signal to vary the intensity of the light from material 18. Disposed between the material 18 and the cathode 12 are two pairs of deflector plates 20 and 22.

As best seen in Figure 2, each member of the pairs of plates 20 and 22 is disposed on the side of the electron stream opposite the other member of the pair. Advantageously, the deflector plates 20 are disposed with their axes at an angle with respect to the axis of the cathode 12 and the material 18. The purpose of this angular relationship is to achieve a torque or twist on the entire sheet-like electron beam. Although the beam is emanating from the elongated cathode 12 in the form of a sheet or plane of electrons directed toward the entire line of fluorescent material 18, the beam will be rotated to a position in which the plane-like sheet is disposed at a slight angle with respect to the fluorescent material. This torque or twist of the sheet of electrons may be produced by a relatively constant electric field emanating from the electrodes 20 as the result of the application of a constant direct current potential from a suitable source such as power supply 19. The second pair of deflector plates 22 has its axis substantially parallel to the axes of the slot 16 and the cathode 12. If a varying voltage such as a sawtooth wave it applied to the second set of plates 22 from supply 19, the canted or twisted sheet of electrons will undergo a deflecting force perpendicular to the plates 22. The area of the fluorescent material 18 which defines the intersection of the canted sheet-like beam and the line of material 18 is energized. Since the canted beam is swept across the material 18, the intersection moves from one end of the material to the other. This movement of the intersection cause-s a selective energization and the emission of light from the discrete areas of the line of fluorescent material 18.

Advantageously, the switching device may be placed adjacent a line of photoelectric devices such as phototransistors and the selective energization of discrete areas of the fluorescent material 18 will cause a selective energization of the adjacent phototransistors. If each of these phototransistors is in a separate circuit, the respective separate circuit will be effectively closed. If a forward bias is normally maintained on the transistors which is just below the threshold value, the transistor will conduct current when energized by the light of the material 18.

One exemplary embodiment of this combination is shown in combined schematic and diagrammatic form in Figure 3. As therein depicted, a first switching device 10 may be associated with a line of phototransistors 26, each of which is associated with a column conductor of the phosphor screen such as conductor 28. Similarly, a second switching device 10A may be employed in conjunction with the row conductors such as 30 and 32. The row conductors such as 28 are serially connected in a circuit which may include the phototransistor 26, a source 34 of potential and a resistor 36. Similarly, the coumn conductors 30 are connected in circuit with a phototransistor such as 40, a source 42 of potential and a resistor 44. Column electrode 32 is connected through a phototransistor 46, source 42 and a resistor 47. The discrete phosphor area intermediate the intersection of conductors 28 and 30 is shown in greatly magnified form as a rectangle 50. In like manner, the intersection of conductors 28 and 32 is defined as an enlarged area 52. In accordance with well known principles as adequately defined in the above-mentioned patents, the selective energization of a column and a row conductor causes the phosphor area intermediate this intersection to be excited and to radiate light. The magnitude of the light radiated from material 18 is pro portional to the magnitude of excitation or velocity of the electrons or the difference in potential between the cathode 12 and anode 17 as applied by source 21. The amount of current flowing in any one of the conductors such as 28 and 30 will be determined by the intensity of illumination incident on the adjacent fluorescent material in the switching devices 10 and 10A, respectively, which are connected to sources of supply 19 and 21, as shown in Figure 1. If a varying signal is applied between the cathode 12 of the respective switching device and the line of fluorescent material 18 by source 21, the amount of illumination produced in the fluorescent material will be correspondingly modulated. Accordingly, it is possibe to produce with this switching device a selective energization of the row and column conductors of a phosphor screen and to vary this energization in accordance with a predetermined signal such as a video signal. It is, of course, understood that in the embodiment shown in Figure 3 the discrete areas 50 and 52 may be separate parallel planes of phosphor material which emit light of different primary colors. Accordingly, it is possible to produce a coor image by the use of a plurality of superposed column conductors with interspersed phosphor layers, each of the column conductors co-operating with one or more of the roW conductors. By various combinations of voltages applied to the deflector plates 20 of the respective switching devices 10 and 10A, it is possible selectively to energize superposed areas of different color emitting phosphor depending upon the particular requirements.

It is not essential to modulate the potential applied between the cathode 12 and the anode 17. Suitable modulation may be applied directly through terminals such as 54, 56 and 58 from a source such as 62 and/or 64. With this arrangement, however, the combination of bias voltages from sources 34 and 42 and modulating voltages such as from source 62 and/or source 64 must not be sufficient to energize the phosphor such as 50 and 52 in the absence of incident light on the associated photo diode 26, 40 or 46.

Any convenient photoelectric device may be employed. However, narrow base germanium photo diodes may be employed to utilize their small physical size and good electrical and physical properties. These diodes are described on pages 1l22-1130, Proceedings of the IRE, vol. 46, No. 6, June 1958.

These novel concepts may be applied to various other embodiments without departing from the spirit and scope of this invention as defined in the claims.

What is claimed is:

1. A device for selectively energizing discrete areas of a line of fluorescent material comprising an elongated line of fluorescent material, a source of electrons positioned remote from said line of material and having its axis substantially parallel to the axis of said material for radiating a transversely elongated beam of electrons, means for rotating the transversely elongated beam of electrons radiated from said source and means for deflecting the rotated beam of electrons whereby selected finite areas of said fluorescent material are energized at the intersection of the rotated elongated beam and the line of fluorescent material.

2. A device according to claim 1 wherein said means for deflecting said elongated beam of electrons comprise a pair of deflector plates, one of said pair being disposed on either side of said line of fluorescent material and between said source and said line.

3. A device according to claim 2 wherein said pair of deflector plates has its axis disposed at an angle with respect to said source and to said line of material.

4. The device according to claim 3 further comprising a second pair of deflector plates, said second pair of plates having its axis positioned parallel to the axis of said line of material and to said source and means for applying a modulated voltage between said source and said material.

5. A device for selectively energizing a plurality of linearly disposed photoelectric elements comprising an elongated envelope having a line of fluorescent material disposed on the interior thereof, an elongated electron source in said envelope having its axis substantially parallel to said fluorescent material for supplying a transversely elongated beam of electrons and means positioned intermediate said source and said material selectively for rotating said beam and deflecting the rotated beam, thereby selectively energizing finite areas of said fluorescent material.

6. The device according to claim 5 wherein said electron source comprises an arcuate cathode having its concave surface directed toward said line of fluorescent material.

7. The device according to claim 6 wherein said arcuate cathode has an emissive coating on the concave surface thereof.

8. The device according to claim 7 wherein said means for deflecting said beam of electrons comprises a first pair of deflector plates positioned intermediate said source and said fluorescent material and having its axis disposed at an angle with respect to the axis of said fluorescent material.

9. The device according to claim 8 wherein said means intermediate said source and said material includes a second pair of deflector plates positioned intermediate said first pair of deflector plates and said fluorescent material.

10. The device according to claim 9 wherein said second pair of deflector plates has its axis disposed in a direction parallel to the axis of said fluorescent material.

References Cited in the file of this patent UNITED STATES PATENTS 1,757,345 Strobel May 6, 1930 2,594,026 Jacobi et a1. Apr. 22, 1952 2,713,650 Sears July 19, 1955 

